my 400 started to overheat and leak coolant out the left top of rad....fan works...going to change rad.cap in morning...checking...took cap off, started motor when cold,put hand over rad. hole and it would build back pressure and blow coolant out...could the head gasket be blown..put new one last fall.. do the heads on 400 have a problem with warping...going to take compression also...what should the comp. read? ...any help appric.thanks

 

Loosen the 10 mm bolt on top rear of head (close to the temp sensor) allow coolant to flow out,check for air bubbles. When you see a steady stream of coolant tighten bolt. Top off coolant in radiator,replace with the new cap and fill overflow bottle. Compression should be between 120-140 on a used engine in good shape. Try this and see if it helps. Heads can warp especially when rebuilds are done and people forget to remove air pockets from the coolant by way of the bleed bolt. Keep us updated. OPT

 

old polaris tech..I found mech. to work on it..I did not do the bleeder bolt when I replace head gasket last fall, but will make sure it is done this time..will post results..thank you

 

old polaris tech...you were rite on...had the the head checked, it was warped..milled it..back together, only have a few miles on it,seems to have solved the problem..thanks

 

thats why he's our tech expert.